Not much, but you can use them in different ways.

e.g. you can do this:

print qq{the "cat" sat {furrily} on the 'so-called' mat};
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without having to escape any of the quotes, or the brackets.

The same is true of a here document (e.g. <<"END") of course, in fact that's more adaptable because it can contain anything at all (except \nEND, obviously), but it takes more than one line.

hth,
andy.